This proposal addresses basic questions about how the vertebrate nervous system is induced and patterned. The gene for Xenopus Frizzled 8 (Xfz8) is widely expressed in presumptive neuroectoderm, and then becomes restricted to anterior neuroectoderm, suggesting that the Xfz8 gene is targeted by signaling pathways important for neural induction and establishment of the anterior-posterior neural axis. This project will use a Xenopus model system to identify the signaling pathways that control Xfz8 expression, as well as the DNA regulatory elements that allow Xfz8 to respond to these signals. These studies will provide new insights into how cells determine their position within an embryo and respond with the correct pattern of gene expression. Understanding these embryonic processes will be important for understanding the molecular mechanisms underlying birth defects. This knowledge should also be of value to cancer biology, because many of the signaling molecules involved in these developmental process may, when expressed abnormally, be a cause of cancer.